メダカ

Adhesion interface between hard tissues like cement lines of bone in mammals shows positive reaction of periodic acid-SCIFF (PAS) staining, and bone sialoprotein (BSP), osteopontin (OPN), and glycosaminoglycans (GAGs) are also detected there. It has been reported that such noncollagenous proteins participate in adhesion between hard tissues. Bone tissue phylogenically appears in Teleost fish. Therefore, it is important to understand the characteristisc of adhesion interface between hard tissues in Teleost fish when the significance of that in mammals is considered. The present study aims to observe adhesion interface between hard tissues, tooth-pedicel-interface(TPI) in upper pharyngeal bone of Japanese medaka, and to clarify the morphological characteristics of them. Upper pharyngeal bone and tooth of Japanese medaka were used in this study. For light microscopic (LM) observation, specimens were embedded in paraffin or resin (LR-white) after fixation, decalcification and dehydration. Slices were made in frontal direction, stained with haematoxylin-eosin(HE), PAS, AZAN, and observed by LM. For transmission electron microscopic (TEM) observation, specimens were embedded in LR-white resin. Ultrathin sections were made in frontal direction and were observed by TEM. By LM, TPI were observed as line-shaped structure without staining of HE and PAS, however there were collagen fibers with AZAN straining. Cement lines were not strained with HE, PAS and AZAN, and they were observed as lines with irregular contours. By TEM, collagen fibers were observed in TPI and there were some fibers connected to those in the matrix of tooth and pedicel. On cement lines there was no structure and only exposed collagen fiber was observed on the surfaces of bone. These findings suggest that TPI have no PAS-positive materials and are made of collagen fibers and and that cement lines are made of only mineral without any collagen fiber and PAS-positive materials.